Well now, hold on...

Comic relief is not an excuse to bend the fundamental rules of the series. Sanji engulfing himself in flames is unrelated, as it is a common characterization used over dramatically in cartoons. It would be different if, say, Sanji was able to use the flames of passion to defeat Aokiji's ice or something.

Perhaps a better scenario to compare it to would be Inner Sakura vs Ino, which is ridiculous considering that Inner Sakura was meant to be a symbolic manifestation of Sakura's passion.

Still bullshit though.